---The meeting’s been put off until next week.

---Sorry, ______. Could you say it again?

A．I didn’t mean that

B．I didn’t know

C．I didn’t take it

D．I didn’t get it

为加速度油珠上浮速度，在污水处理时要加入（）。

A.水

B.泥

C.盐

D.混凝剂